Method for determining strain of under-grid barrier layer of GaN heterojunction field effect transistor

Abstract

The invention provides a method for determining the strain of an under-grid barrier layer of a GaN heterojunction field effect transistor, and belongs to the technical field of microelectronics. According to the basic principle of the method, firstly, a semiconductor parameter tester is used for directly obtaining a characteristic curve of capacitance-voltage (C-V) and forward current-voltage (I-V) between a grid electrode and a source electrode of the GaN heterojunction field effect transistor, total under-grid polarization charge density is obtained in combination with barrier layer capacitance analysis, and then the strain of the under-grid barrier layer of the GaN heterojunction field effect transistor is obtained through analysis according to the theories of spontaneous polarization and piezoelectric polarization of GaN heterojunction materials. Compared with existing testing technologies, the testing method is easier, direct and accurate, the resolution ratio is higher, and the problem that an existing testing method cannot test the strain of the under-grid barrier layer is solved.

Description

technical field [0001] The invention relates to a method for determining the strain of a potential barrier layer under the gate of a GaN heterojunction field effect transistor, belonging to the technical field of microelectronics. Background technique [0002] In recent years, GaN heterojunction field-effect transistors (HFETs) have been attracting much attention as a research hotspot in the field of microelectronics due to their wide application prospects in high temperature, high frequency and high power. Studies have shown that polarization charges are crucial to the electrical properties of GaN heterojunction field effect transistors, and polarization is closely related to the strain of the barrier layer. Therefore, obtaining the strain information of the AlGaN barrier layer is very important for improving the device characteristics of GaN HFETs to important. At present, micro-area Raman spectroscopy is one of the main methods to study the strain of the barrier layer. I...

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Problems solved by technology

At present, micro-area Raman spectroscopy is one of the main methods to study the strain of the barrier layer. In 2004, Sarus et al. published "Al X Ga 1-x N's E 2 (High) Phonon Mode Phonon Deformation Potential" and "Piezoelectric Polarization Tensile Strain of AlGaN / GaN Heterojunction Field-Effect Transistor under Bias" published by Sarua et al. in Applied Physics Letters No. 88, p. " and other articles have used the method of micro-area Raman spectroscopy to study the strain of the barrier layer. Micro-area Raman spectroscopy provides a non-destructive method for measuring the stress and distribution of the epitaxial layer. In the phonon Raman peak, E. 2 The Raman scattering of the (high) phonon mode is allowed in the backscattering mode of the (0001) surface, and the half-maximum width is narrow and the intensity is large; generally, the E 2 The Raman peak frequency shift of the (high) phonon mode is used to measure the stress of the GaN layer, and then the relationship between the action force and the reaction force is used to deduce the strain information of the barrier layer. However, due to the large test spot, the resolution of this method is relatively low. As for the strain of the barrier layer under the gate, due to the blocking of the gate metal, light cannot enter from the front, and the back substrate is thicker, so it is very difficult to test and analyze the strain of the barrier layer under the gate metal which is very thin

So far there is no method to measure the strain of the barrier layer under the gate

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